package UDP;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoServer {
    private int port;
    private DatagramSocket socket;
    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    public void start() throws IOException {
        System.out.println("服务器启动！");
        while(true) {
            //1.请求解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //2.将存储在requestPacket中的byte数组给转换成String
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
            //3.根据请求计算响应,这里我的请求就是响应，响应就是请求
            String response = process(request);
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(responsePacket);
            //4.打印日志，打印每一次客户端与服务器交互的过程
            System.out.printf("[%s:%d] req = %s, resp = %s",requestPacket.getAddress().toString(),
                    requestPacket.getPort(),request,response);

        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9650);
        server.start();
    }
}
